Due to rapid growth in use and application of digital information technology, there are demands to continuingly increase the memory density of memory devices while maintaining, if not reducing, the size of the devices. Three-dimensional (3D) structures have been investigated for increasing the memory density of a device. For example, 3D cross-point memory cells have been investigated as devices having increased capacity and smaller critical dimensions. These 3D semiconductor structures typically include stacks of materials on a substrate. The materials include phase change materials, switching diode elements, charge storage structures (e.g., floating gates, charge traps, tunneling dielectrics), and charge blocking materials between the charge storage structures and adjacent control gates.
Fabricating these 3D structures often requires forming high aspect ratio features from the stacks of materials. Frequently, materials that are sensitive to downstream processing conditions are present in the stacks. For example, stacks in 3D cross-point memory cells may include materials, such as chalcogenide materials, carbon-containing electrodes, and other sensitive materials, that may be damaged at the temperatures used during conventional semiconductor fabrication processes or may react with etchants used during downstream processing. For instance, chalcogenide materials in the stacks may volatilize during conventional deposition techniques, causing delamination of the stack materials. To protect the stacks, liners have been formed over the materials of the stack before the subsequent processing acts are conducted. In order to prevent damage to the materials of the stacks, a liner must be formed by a highly conformal deposition technique and must be formed using gentle deposition conditions. In addition, the liner must be formed of a high quality material. The liner must also adhere to the different materials of the stacks. Conventional liners, which are formed of a single material, such as silicon oxide or silicon nitride, do not meet these requirements because gentle deposition conditions and good adhesion are typically at odds with high quality and high conformality because deposition techniques that produce high quality, highly conformal materials damage chalcogenide materials of the stack and degrade adhesion. Conventional techniques for improving the step coverage and quality of the single material liners damage chalcogenide materials and degrade adhesion. Therefore, it would be desirable to produce a high quality, highly conformal liner that is formed under gentle deposition conditions and provides good adhesion to the underlying materials.